<template>
  <canvas
    v-if="canvasId"
    :id="canvasId"
    :type="forceUseOldCanvas?'':'2d'"
    class="ec-canvas"
    :canvasId="canvasId"
    @touchstart="touchStart"
    @touchmove="touchMove"
    @touchend="touchEnd"
  />
</template>

<script>
import WxCanvas2 from './wx-canvas2'
import WxCanvas from './wx-canvas'

function compareVersion(v1s, v2s) {
  const v1 = v1s.split('.')
  const v2 = v2s.split('.')
  const len = Math.max(v1.length, v2.length)

  while (v1.length < len) {
    v1.push('0')
  }
  while (v2.length < len) {
    v2.push('0')
  }

  for (let i = 0; i < len; i += 1) {
    const num1 = parseInt(v1[i])
    const num2 = parseInt(v2[i])

    if (num1 > num2) {
      return 1
    } if (num1 < num2) {
      return -1
    }
  }
  return 0
}

function wrapTouch(e) {
  for (let i = 0; i < e.touches.length; i += 1) {
    const touch = e.touches[i]
    touch.offsetX = touch.x
    touch.offsetY = touch.y
  }
  return e
}

export default {
  props: {
    echarts: {
      required: true,
      type: Object,
      default() {
        return null
      },
    },
    forceUseOldCanvas: {
      type: Boolean,
      default: false,
    },
    canvasId: {
      type: String,
      default: 'ec-canvas',
    },
    onInit: {
      type: Function,
      default: null,
    },
    lazyLoad: {
      type: Boolean,
      default: false,
    },
    disableTouch: {
      type: Boolean,
      default: false,
    },
    throttleTouch: {
      type: Boolean,
      default: false,
    },
  },

  mounted() {
    if (!this.echarts) {
      console.warn('组件需绑定 echarts 变量，例：<ec-canvas id="mychart-dom-bar" '
        + 'canvas-id="mychart-bar" :echarts="echarts"></ec-canvas>')
      return
    }

    if (!this.lazyLoad) {
      this.init()
    }
  },

  methods: {
    init(callback) {
      const version = wx.getSystemInfoSync().SDKVersion

      const canUseNewCanvas = compareVersion(version, '2.9.0') >= 0
      this.isUseNewCanvas = canUseNewCanvas && !this.forceUseOldCanvas

      if (this.forceUseOldCanvas && canUseNewCanvas) {
        console.warn('开发者强制使用旧canvas,建议关闭')
      }

      if (this.isUseNewCanvas) {
        this.initByNewWay(callback)
      } else {
        const isValid = compareVersion(version, '1.9.91') >= 0
        if (!isValid) {
          console.error('微信基础库版本过低，需大于等于 1.9.91。'
            + '参见：https://github.com/ecomfe/echarts-for-weixin'
            + '#%E5%BE%AE%E4%BF%A1%E7%89%88%E6%9C%AC%E8%A6%81%E6%B1%82')
        } else {
          console.warn('建议将微信基础库调整大于等于2.9.0版本。升级后绘图将有更好性能')
          this.initByOldWay(callback)
        }
      }
    },
    initByNewWay(callback) {
      // version >= 2.9.0：使用新的方式初始化
      const { canvasId } = this
      const query = wx.createSelectorQuery().in(this)

      query
        .select(`#${canvasId}`)
        .fields({ node: true, size: true })
        .exec((res) => {
          const canvasNode = res[0].node
          this.canvasNode = canvasNode

          const canvasDpr = wx.getSystemInfoSync().pixelRatio
          const canvasWidth = res[0].width
          const canvasHeight = res[0].height

          const ctx = canvasNode.getContext('2d')

          const canvas = new WxCanvas2(ctx, canvasId, true, canvasNode)
          this.echarts.setCanvasCreator(() => canvas)

          if (typeof callback === 'function') {
            this.chart = callback(canvas, canvasWidth, canvasHeight, canvasDpr)
          } else if (typeof this.onInit === 'function') {
            this.chart = this.onInit(canvas, canvasWidth, canvasHeight, canvasDpr)
          } else {
            this.triggerEvent('init', {
              canvas,
              width: canvasWidth,
              height: canvasHeight,
              dpr: canvasDpr,
            })
          }
        })
    },
    initByOldWay(callback) {
      // 1.9.91 <= version < 2.9.0：原来的方式初始化
      const canvasId = this.canvasId
      this.ctx = wx.createCanvasContext(canvasId, this)

      const canvas = new WxCanvas(this.ctx, canvasId)

      this.echarts.setCanvasCreator(() => canvas)
      // const canvasDpr = wx.getSystemInfoSync().pixelRatio // 微信旧的canvas不能传入dpr
      const canvasDpr = 1

      const query = wx.createSelectorQuery().in(this)
      query.select(`#${canvasId}`).boundingClientRect((res) => {
        if (!res) {
          setTimeout(() => this.init(), 50)
          return
        }

        const { width, height } = res

        if (typeof callback === 'function') {
          this.chart = callback(canvas, width, height, canvasDpr)
        } else if (typeof this.onInit === 'function') {
          this.chart = this.onInit(canvas, width, height, canvasDpr)
        } else {
          this.triggerEvent('init', {
            canvas,
            width,
            height,
            dpr: canvasDpr,
          })
        }
      }).exec()
    },
    canvasToTempFilePath(opt) {
      const { canvasId } = this
      if (this.isUseNewCanvas) {
        // 新版
        const query = wx.createSelectorQuery().in(this)
        query
          .select(`#${canvasId}`)
          .fields({ node: true, size: true })
          .exec((res) => {
            const canvasNode = res[0].node
            Object.assign(opt, { canvas: canvasNode })
            wx.canvasToTempFilePath(opt)
          })
      } else {
        // 旧的
        this.ctx.draw(true, () => {
          wx.canvasToTempFilePath({
            canvasId,
            ...opt,
          })
        })
      }
    },
    touchStart(e) {
      const { disableTouch, chart } = this
      if (disableTouch || !chart || !e.touches.length) return

      const touch = e.touches[0]
      const { handler } = chart.getZr()
      handler.dispatch('mousedown', {
        zrX: touch.x,
        zrY: touch.y,
      })
      handler.dispatch('mousemove', {
        zrX: touch.x,
        zrY: touch.y,
      })
      handler.processGesture(wrapTouch(e), 'start')
    },
    touchMove(e) {
      const {
        disableTouch, throttleTouch, chart, lastMoveTime,
      } = this
      if (disableTouch || !chart || !e.touches.length) return

      if (throttleTouch) {
        const currMoveTime = Date.now()
        if (currMoveTime - lastMoveTime < 240) return
        this.lastMoveTime = currMoveTime
      }

      const touch = e.touches[0]
      const { handler } = chart.getZr()
      handler.dispatch('mousemove', {
        zrX: touch.x,
        zrY: touch.y,
      })
      handler.processGesture(wrapTouch(e), 'change')
    },
    touchEnd(e) {
      const { disableTouch, chart } = this
      if (disableTouch || !chart) return
      const touch = e.changedTouches ? e.changedTouches[0] : {}
      const { handler } = chart.getZr()
      handler.dispatch('mouseup', {
        zrX: touch.x,
        zrY: touch.y,
      })
      handler.dispatch('click', {
        zrX: touch.x,
        zrY: touch.y,
      })
      handler.processGesture(wrapTouch(e), 'end')
    },
  },
}
</script>

<style scoped>
.ec-canvas {
  width: 100%;
  height: 100%;
}
</style>
